Misc fixes pointed out by Eclipse PyDev static code analysis

Here's fixes for a few scipy issues pointed out by my editor (Eclipse PyDev).
I'm not familiar with the code and didn't test, so please check the changes carefully.

There's two more that I think might be real issues where I don't know what the correct fix is:
```
Description	Resource	Path	Location	Type
Undefined variable: get_psolve	iterative.py	/scipy/scipy/sparse/linalg/isolve	line 198	PyDev Problem
Undefined variable: ct	hb.py	/scipy/scipy/io/harwell_boeing	line 257	PyDev Problem
```
https://coveralls.io/files/59355318#L199
https://coveralls.io/files/59355112#L258

All of these issues are not covered by unit tests.